1. Field of the Invention
The present invention relates to a review control method of a video cassette recorder, in particular, for implementing a review operation without noises on a screen in switching from a play mode into a review mode.
2. Description of the Related Art
A video cassette recorder uses a capstan 7 and a pinch roller 9 to run a tape at a regulated rate. The capstan 7 performs loading/unloading under the force of the capstan motor 8, and provides a force for running the tape. The pinch roller 9 is closely contacted with the capstan 7, and functions to pull the tape in a specific running direction. In addition to the foregoing components, a tension belt 4 can be included as a component that is used for running the tape. The tension belt 4 is used to uniformly maintain a tension applied to the tape in a running mode such as a play mode for regenerating the tape while running the same.
In a conventional video cassette recorder having the foregoing configuration, a configuration of mechanical modes is as shown in FIG. 1.
In a play mode PLAY, the pinch roller 9 maintains a compressed state, and a tension band brake 5 has an operation state On. A supply reel brake 13 and a turning-up reel brake 15 are released having off states Off to help forward running of the tape. FIG. 2 illustrates the components in such a play mode PLAY.
In a review mode REV, the tension band brake 5 switches into a released off state Off from the play mode PLAY, and the turning-up reel brake 15 is turned on into an operating or on state to help review. FIG. 3 illustrates the components in such a review mode REV.
As shown above, the pinch roller 9 has the compressed state in all ranges of the play mode PLAY and the review mode REV. A video cassette tape with such a configuration tends to have noises due to droop of the tape when switching from the play mode PLAY to the review mode REV.
Therefore, the conventional video cassette recorder performs operation processes as shown in FIG. 4 in order to solve the problems as set forth above.
When a key is inputted for switching to the review mode REV during operation in the play mode PLAY, a control unit (not shown) reverses a loading motor (not shown) while rotating forward the capstan motor 8 continuously at a basic rate so as to be positioned in a loading end mode L/D END where the pinch roller 9 has a decompressed off state Off. When positioned in the loading end mode L/D END in this operation, the capstan motor 8 and the loading motor are stopped. This operation state is shown in a range A in FIG. 4.
Then, the capstan motor 8 is reversed at a predetermined amount. This operation moves an idle roller 10 toward a supply reel 3. Then, the capstan motor 8 is stopped.
After the capstan motor 8 is stopped and the loading motor is forward rotated into the review mode REV, the capstan motor 8 is reversed to carry out the review operation. This operation state is shown in a range B in FIG. 4.
In the foregoing operation, the supply reel brake 13 switches from an off state into an on state and then returns to the off state in order to prevent the tape from being unwound from the supply reel 3. Switching the turning-up reel brake 15 from the off state into the on state is necessary to stabilize a running path of the tape by applying back tension to the tape in the review operation.
In other words, the taped is drooped while the tension band brake 5 is switched from an on operation into an off operation in switching of the conventional video cassette from the play mode PLAY into the review node REV. The drooping of the tape is controlled by continuously forward rotating the capstan motor 8 on the loading end mode L/D END where the pinch roller 9 has the off state Off.
However, the review control method of the conventional video cassette recorder operating in such a manner brings about the following problems.
The turning-up reel brake 15 is necessarily switched into the on state in the range of the play mode PLAY and the review mode REV in order to progress the review mode. The brake torque of the turning-up reel brake 15 acts as the load on the turning-up reel 1 as soon as the turning-up reel brake 15 is on. Therefore, the rotation torque of the tinning-up reel 3 decreases as much as the brake torque acting as above. If the forward torque of a friction clutch 12 is not sufficiently larger than the load torque of the turning-up reel brake 15 due to such actions, the tape is unwound (the turning-up reel is incapable of rotating) after the pinch roller 9 in the range A in FIG. 4 and noises due to the tape drooping take place from a time point, when the pinch roller 9 is off, in the range B.
If the forward torque of the clutch 12 is set high to solve the foregoing problem, the capstan motor 8 is barely stopped at a correct position Moreover, a clutch friction member is abraded to lower the reliability of a product.